Scientific evidences acknowledged the yacon (Smallanthus sonchifolius) like a promise source of fructans, as inulin and fructooligosaccharides - FOS, meanwhile, the presence of phenolic coumpounds became this susceptible to enzimatic browning reaction. This project aimed to evaluate the use of chemical agents in yacon processing to obtain flour in a way that inhibits enzymatic darkening of the product besides determining the enzymatic activity in these treatments. Samples of yacon without chemical inhibitions, yacon treated with 1.0g 100g-1 calcium chloride for 30 seconds and yacon treated with 0.5g 100g-1 potassium metabisulfite for 5 minutes were dried at 55oC in a ventilated greenhouse and the proportions of humidity and drying curves were determined. The peroxidase activities and polyphenol oxidase enzymes were checked before and after being dried with an enzymatic darkening possible biochemist marker of this tubercle. Regarding humidity Parameter all the three treatment were equivalent, but treatment 2 (calcium chloride) reduced the humidity in lower time. Before and after the thermal treatment the enzymatic activity was higher in treatment 3 (potassium metabisulfite). The thermal action did not inhibit completely polyphenol oxidase and peroxidase. The treatment with calcium chloride at 1.0g 100g-1 for 30 minutes to obtain yacon flour was the one with better result despite the fact that it did not inhibit completely peroxidase and polyphenol oxidase enzymes activity, offering a better drying time better material of row firmness , facilitating the process for obtaining the meal.